In recent years, in addition to a mouse, a pen tablet, and a touchpad which serve as input devices with which data is input to a computer and the like, a data input technique in which data is input by using a user's movement or posture has been studied.
For example, a human interface technique is known in which the shape of a user's hand is extracted from an image and a command corresponding to the shape is input. There is, for example, an input system that recognizes which of five fingers is or are raised and inputs various instructions to a computer or the like. The input system is disclosed in Japanese Laid-open Patent Publication No. 2003-346162.
The input system converts an input image into an image in a hue-saturation-value (HSV) color system so as to extract a skin color component. Then, the image is binarized into the skin color component and the other components, and an area having a maximum area in an obtained binary image is extracted. Furthermore, a smoothing process or the like is performed and a hand area in the image is thereby determined. Then, the input system recognizes the shape of the hand area and inputs various instructions.